REPORT 


ON THE a kee 


COLLECTION AND TREATMENT 


OF THE 


G Z 
3 ZY 
SEWAGE % (* 
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OF THE Qe & 
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CITY OF NEW HAVEN, CONN. “Cr, 


DECEMBER 1, 1926 


FULLER & McCLINTOCK 
170 BROADWAY 
NEW YORK 


REPORT 


ON THE 


COLLECTION AND TREATMENT 


OF THE 


SEWAGE 


OF THE 


CITY OF NEW HAVEN, CONN. 


DECEMBER 1, 1926 


FULLER & McCLINTOCK 
170 BROADWAY 
NEW YORK 


ko 


ka. 


DECEMBER I, 1920. 


Honorable John B. Tower, Mayor, 
City of New Haven, Conn. 


DEAR Sir: 


As authorized on March 5, 1926, we have made a study 
of sewerage and sewage disposal conditions in the City of 
New Haven and adjacent territory. We report herewith 
our findings and recommendations, to which is attached a 
summary of supporting data. 


GENERAL CONDITIONS. 


1.—The City of New Haven has a population of over 
180,000 with a water supply pains about 24 million 
gallons daily. 


2.—The sewerage system comprises approximately 155 
miles of sewers, and with the exception of three wards 
on the eastern shore of the harbor, very few streets are 
without sewerage facilities. It is on the combined plan, 
transporting sanitary sewage and storm water in the same 
pipe lines, excepting in the Westville district, which is 
provided with some 10 miles of separate sanitary sewers, 
and 5 miles of storm water conduits. Sanitary sewers 
serving a population of approximately 4,500 in the town 
of Hamden, north of the City, empty into the City sewers, 
under agreement between the two municipalities. 


3.—Sewage and industrial wastes are discharged un- 
treated into the inner harbor and the West, Mill and 
Quinnipiac Rivers, about 90 per cent. being carried by the 
five main outfall sewers, and the remainder by numerous 
private sewers and drains from industries and residences. 
The location of the main outlets is shown on Plate I. 


36579 


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MAIN OUTFALLS AND 
STORM WATER OVERFLOWS 


3 


4.—There are eighteen storm overflows on the main 
sewers which discharge a portion of the excess flow of 
sewage and rain water into the harbor and rivers during 
storms. Some of these overflows are at such elevations 
as to operate during light storms, discharging sewage into 
the rivers, when there is but little clean water available 
for dilution. 


CONDITION OF HARBOR AND TRIBUTARY STREAMS. 


5.—Insanitary conditions have long existed to a serious 
degree in the harbor and Mill River, and to a lesser extent 
in West and Quinnipiac Rivers, due to discharge of un- 
treated sewage and industrial wastes. Manifestations of 
these insanitary conditions include the following:— 


(a) Bathing Beach Pollution. The waters of the 
entire harbor are polluted, constituting a menace to 
public health of greater proportions than generally 
realized. Should numerous cases of typhoid fever, or 
other water-borne disease, appear in New Haven, re- 
gardless of the source of infection, the present method 
of sewage disposal would make the existing pollution 
of bathing beaches a very serious matter. This danger 
has been emphasized by the City Board of Health 
during the past years. 

(b) Relation to Shellfish. The State of Connecticut 
prohibits the direct marketing of oysters from all of 
the harbor above a line between Oyster River Point 
and Old Light, because of widespread danger of disease 
which would result through shipment of the oysters. 
Owing to the continued presence of sewage bacteria 
in large numbers in the outer harbor, it has been 
recently proposed to move this line outward so as to 
extend from Oyster River Point to Morgans Point. 

(c) Sludge Deposits. The discharge of thousands 
of tons of settleable sewage solids each year has formed 
accumulations of putrescible matter on the bed of the 
harbor and its branches, ranging in depth from a few 


4 


inches to over ten feet. The decomposition of these 
solids during warm weather exhausts the oxygen 
naturally contained in the harbor water, interferes with 
fish life, and causes objectionable odors discernible at 
considerable distances from the water front. 

(d) Sewage Mud Flats. In the relatively shallow 
inner harbor and the lower stretches of the rivers, 
where large areas of foul deposits are exposed at 
low tide, conditions are particularly disgusting to sight 
and smell, and constitute an additional menace to public 
health, in that flies may carry infection to nearby 
markets and homes. 

(e) Appearance of Harbor. Oil sleek on the harbor 
and rivers, increase of floating solids, and discoloration 
due to dye works wastes, show the absence of a suitable 
standard in this branch of municipal cleanliness. 


The above conditions generally are prejudicial to con- 
tinued development of the City, in that they needlessly 
hazard property values along the water fronts. 


CONCLUSIONS AS TO NEEDED TREATMENT AND DISPOSAL 
OF SEWAGE. 


6.—Outfall Into Long Island Sound Too Expensive. 
The disposal of the sewage through long outfalls into the 
deep waters of Long Island Sound would involve greater 
construction costs than for other methods of disposal, and 
require expensive pumping facilities. Furthermore such 
disposal could not be considered as complying with the 
general program for protection and improvement of coastal 
waters instituted by the State Department of Health, the 
State Water Commission, and the State Shellfish Com- 
mission. 


7.—Treaiment Necessary. Sewage treatment should 
eliminate visible evidence of sewage from the waters of 
the harbor and rivers; should prevent formation of extensive 


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Pj eee Present City. Limits 


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fj --——furfure Jewerage District Limits . - © z 
ij---—-- Storm Water Relief Sewers eZ 

intercepting Sewers \\ a 


Boulevard Sedimentation Tanks 


Meadow Sit a ” 
BOST OF if if 
Eastern Shore if u 


James St Grit Chamber 
Forbes Ave. Pumping Station 
District Pumping Stations 
Jludge Digestion Site 
(A/ternate Project. 


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NEW . HAVEN 


Scace in Feet 


SR ER SN ee NT TN NS eT 
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! Oyster River Pt. RELIEF SEWERS & TREATMENT PLANTS 


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sludge banks; and should reduce bacterial content so as 
not to dangerously pollute bathing beaches or shellfish 
layings at the mouth of the harbor. The complete purifica- 
tion of sewage will not be necessary to subserve the general 
interests of the public health for some years to come. 


8.—Screens Inadequate. Sewage treatment by fine 
screens alone is not adequate for local conditions. The 
removal of from five to fifteen per cent. of sewage filth 
would not prevent the formation of sludge deposits on 
the harbor bottom, as the population increases through a 
term of years, nor would such degree of clarification be 
commensurate with the cost. 


9.—Sedimentation Needed. Adequate removal of settle- 
able solids can be effected in suitably designed plain sedi- 
mentation tanks which will remove from fifty to seventy 
per cent. of the organic solids and bacteria from the sewage, 
or ninety per cent. or more of the readily settleable solids. 
This removal is equivalent to from four to ten times that 
which would be effected by fine screens. Chambers should 
be provided for removal of grit carried by the sewage, and 
for skimming grease floating on the surface. Sludge should 
be collected in suitable sumps by mechanical scrapers, or 
other devices, before decomposition begins. 


10.—Location of Suitable Treatment Works. There 
should be four sedimentation plants, three being located 
adjacent to the present Boulevard, Meadow and East Street 
outfalls, and the fourth on meadow land near the northern 
end of Nathan Hale Park on the eastern shore. This latter 
plant would receive sewage from James and Poplar Street 
outfalls, and from sewers to be installed in the eastern 
shore districts, and is the only one where pumping of the 
sewage would be required. The general locations of the 
sedimentation plants and intercepting sewers are shown 
on: Plate IT. 


6 


11.—-Chlorination. To protect bathing beaches against 
pollution by the sewage, the tank effluent should be treated 
with chlorine gas as a germicide. The application of 
about 45 pounds of chlorine gas to each million gallons of 
sewage passing through the tanks is ordinarily sufficient. 
The duration of the chlorination period will depend to a 
large extent upon the future location, use and condition 
of bathing beaches, but will probably be from three to four 
months each year. 


12.—Capacity of Sewage Treatment Works. Construc- 
tion of sewage treatment works should be undertaken 
promptly under a progressive program whereby the first 
installations will provide capacity for treatment of sewage 
flow as expected in about the year 1940 (estimated popula- 
tion 240,500), with arrangements for convenient extension 
as required to about the year 1970. In 1940 an average dry 
weather flow of approximately 33.6 million gallons a day 
can be expected, and in 1970 a corresponding flow of ap- 
proximately 55.75 million gallons daily. In addition to 
sanitary sewage and industrial wastes, the first flush of 
storm water from the streets should be delivered to the 
treatment works by suitable regulators. 


13.—Sludge Disposal. Consideration has been given to 
two methods of disposal of the sewage solids removed 
daily as sludge from the bottom of the sedimentation tanks. 
One method would be to pump the sludge through cast 
iron pipe lines to separate sludge digestion tanks which 
would be located in East Haven in the farming district in 
the general vicinity of the State Rifle Range. Here the 
sludge would be mixed and limed in masonry tanks equipped 
with collectors so that the gases would not escape into the 
atmosphere, but could be burned or utilized as desired. The 
thoroughly digested and inodorous sludge would be de- 
watered on underdrained sand beds. The dry solids could 
then be used for filling, or as a fertilizer, and the liquid 
returned to the sedimentation tanks through the connecting 


7 


pipe lines. Such a method is in successful use in numerous 
places in England and Germany, and is coming into vogue 
in this country. 

As an alternate arrangement we have considered the 
collecticn of sludge in holding or decantation compart- 
ments adjacent to the several sedimentation plants, from 
which it would be discharged into tank steamers resembling 
“oil tankers’, and disposed of in the open ocean. This 
is the method practiced by every sizable seacoast city in 
Great Britain, and by the Passaic Valley Sewerage District 
in New Jersey. 

Of these two methods, it is our opinion that disposal 
at sea is the cheaper and simpler under local conditions, and 
it is accordingly embodied in our recommended project. 


SEWER SYSTEM DEFICIENCIES. 


14.—Replacement Sewers. Some of the older sewers, 
constructed for the most part prior to adoption of the 
Chesbrough plan in 1872, are commencing to disintegrate, 
or are so worn by continued scour of mineral matters that 
replacement is necessary. The length of these sewers is 
approximately 2.5 miles, and replacement costs are estimated 
at $175,000. Sewer construction and maintenance in gen- 
eral, has been excellent throughout the City. 


15.—Rehef Sewers. Overloading or surcharging of 
sewers, with backflooding of cellars, occurs in several sec- 
tions of the City during intense storms. This condition 
is quite generally encountered in the larger cities having 
combined sewers constructed many years ago, and is largely 
due to the greater prevalence of impervious street pavements 
and sidewalks, paving of yards, closer spacing of buildings, 
and similar conditions associated with development of the 
City, and which cause more rapid concentration of storm 
water in the sewers. It is also partially due to extension of 
sewers into territory not contemplated in the original design. 

Backflooding of cellars is experienced at frequent inter- 


8 


vals in portions of Church Street from George to Elm; in 
Orange and State Streets from George to Bradley; Temple 
from Crown to Trumbull; Lincoln from Trumbull to 
north of Bradley; Chapel from College to Olive; Court 
from Church to Olive; Elm from College to Orange; Oak 
from Broad to Congress; Congress from Lafayette to 
Meadow; Meadow from Congress to Whiting; Orange 
from Lawrence to Willow; Livingston from Edwards to 
Canner; Winchester from Sachen to Ivy; Canal from 
Bristol to Munson, and in Division and Starr from Win- 
chester to west of Newhall. | 

Relief sewers for these districts can be installed as 
shown on Plate IH, and will total 12.3 miles in length, 
involving expenditures of $675,000. at the present time, 
and an additional estimated sum of $1,500,000., distributed 
over the next 15 to 20 years. 


SEWER EXTENSIONS. 


16.—Future Districts. To maintain the rivers reason- 
ably free from sewage pollution, and to protect the sources 
of public water supply, it is desirable to extend the City 
sewer system to the north and east into Woodbridge, North 
Haven, East Haven, and additional districts of Hamden, 
to the approximate limits shown on Plate II, under agree- 
ment with the respective municipalities providing for re- 
imbursement for additional construction costs and operating 
charges required for transportation and treatment of the 
sewage from such portions of these communities as will 
flow through the City territory. 


17. Iype of Sewers. The existing system of combined 
sewers should be maintained in service, and the separate 
system of sewerage, which has been installed in the Wood- 
bridge district and the town of Hamden, should be adopted 
for the eastern shore wards, and also for the suburban 
districts which will ultimately form portions of the gen- 
eral sewerage system. 


9 


ESTIMATED Cost OF IMMEDIATE CONSTRUCTION PROGRAM. 


Estimated construction costs for the various works, ex- 
cluding land acquisition, are given in the following table: 


PRU RIOeIC ROG W CLSat a line sihaGetirok nee le ase as $175,000. 
POCO WELS TE te eerie ieee ais 675,000. 
Saerrrryy ALCL MINeOUlAtO Cag chien te ers ein as", 65,000. © 
Eastern Shore District: 
Porerceptine dnGsLrunk OeWeLst.. west. s,0 385,000. 
Vee” AON sm ee ee arias aut a eae ets 175,000. 


Sewage Treatment Works: 
Boulevard Sedimentation Plant capacity 8.5 


HAT a aM WELT S.A A a ean rae lS Oe atoll 375,000. 

Meadow Street Sedimentation Plant capacity 
Bruni L Aa ioeaC ally eyese he ee te ela crn at viata: 275,000. 

East Street Sedimentation Plant capacity 
Bevel OA ae Voc tte es Ae ield ewig we ee epee 475,000. 

Eastern Shore Sedimentation Plant capacity 
Eerste oie CLA Vette ce en eee ne testa ss 300,000. 
TES POAT Mer Ff alirin Poise lepal. ahd ye efoheis. ein ohh 100,000. 
$3,000,000. 


Very truly yours, 
FULLER & McCLINTOCK, 
By GeorcE W. FULLER. 


10 


SUPPORTING DATA 
DESCRIPTIVE OF PRESENT CONDITIONS AT 
NEW HAVEN 
AND 
PROGRAM FOR IMPROVEMENTS. 


PAGE 

1.—Conditions in New Haven Harbor and Tribu- 
tary (Streaiis 25. aate ss We ee 12-15 
2,—-Sewage Treatment. “Propramt (2-03 9.0 o. amet 15-20 
Available’ Sites i771 50 os cent see 15 
Development of Sedimentation Process.... 15 
Plain Sedinientation Tanks /..\,; 7). seen 16 
Grif Chambers v5 Wins 8 eee ee ee Ly 
Disposal of Sludge at Sea ney. sa eee ce 17 
separate SludpeDicestion: jaa 19-7) ee ee 18 
Improvements in Sludge Digestion ....... 18 
sludge:Dewatering 4:72, pean ae eee 19 
Miles -AcidProcess) 00). :\k ales. 3a aes 19 
Conclitsions) <>.) 4 sae to heen a 20 
3.—Treatment Works Recommended ............ 20-24 
Capacities i. o5i.4'5 ak ear eearegteg Chars alee eee 20 
Filevations oi. 2 eas ae ie hate ane eee 21 
Regulators ort ee ey sere ce ae 21 
Screens and Grit’ Ghambers 449) ho, 21 
Sedimentation Vanke ts .002n ei. a aes 22 
sludge Disposal: ate Seager to cee ee eee 22 
Separate Sludge Digestion nye ees ae 
plidgvestorce: Mains (i cs ees 23 
Sludge Digestion Tanks corn vee ee 23 
pludge Beds). a ee en ee 24 
4,— Storm: Water ‘Reliel Sewers 2.02 ie nee ae 24-28 
Storm: Water: QOverflows it.) 00) 3. cls eee 26 
Location of Relief Sewers) 4.0: 2 cee 26 
Immediate Construction) 2... 2.2.57 Prk 26 
Meadow, Street, District 77.) (uacnmees 26 


East! Street District) uae eee 26 


zi] 


TaemmOmearerooraails we merit. a7 

Boulevards Wietkiete ws ok eats 27 

Meadow Street»loistrict? 3. aya. 8 27 

Paet ULeCOta IS LEICt oni MOG, o Ruts Sule oy 27 

Pott mea Vets ast LIIStrictn ast. ie steele cs 28 

ereatmetiinG ty OLOrRRe VW ALC ie kcwwin see 2 28 
5.—Extent of Adoption of Separate System of 

PIGWOT CS Merit EIULiILE penarae tai tus any in ye et 28-31 
Extent of Future Sewerage District outside 

Clb ates toner uranic em ianie Aare te ge AI 30 

Eastern Shore Pumping Stations ........ 31 

Sie TIGLCASCO IP ODUIALION ete cial oc lubaiis eben eda) > 31-34 

Commercial and Industrial Areas ois. 5 0 « 32 

eee W OCT IOW ETS ls co.cc Ub MM eet catia v at da Waal’ g large « 34-37 

Industrial and Commercial Sewage Flow.. 35 

HI OMESLICI SEWAGE EMO, Soh occ Corl glee’ sia 36 


8.—Composition of Sewage and Industrial Wastes. 37-38 
EX GRNOWICCOIIET tS chit. cI G0UNs inl cg ot ote 8 ein) ese fu 39 


4 


I.—CONDITIONS IN NEw HAVEN HARBOR AND TRIBUTARY 
STREAMS. 


Deposits réaching’ a maximum depth of more than 10 
feet were found in the inner harbor west and south of 
Long Wharf’ in ‘the vicinity of the Meadow Street and 
Boulevard outfalls. In the eastern portion of the harbor, 
deposits at places reach a depth of from two to three feet: 
In Mill River’ above Chapel Street depths of over three 
feet were recorded. The eastern shore is practically free 
from deposits. Sep! ie 

The putrefaction of the thousands of tons of sludge 
deposits which have accumulated on the harbor floor in- 
creases the total oxygen demand much above that of the 
fresh incoming sewage, and, by exhaustion of the oxygen 
from immediately overlying water, cause local nuisances. 

Over four billion gallons of water enter New Haven 
harbor from Long Island Sound twice a day on normal 
flood tides. The discharge of raw sewage and industrial 
wastes approximates 25 million gallons a day. If this 
sewage could be thoroughly mixed with such a volume of 
new unpolluted sea water, and entirely removed from the 
harbor on each tide, it would be more than sufficient to 
dilute and assimilate the sewage without nuisance or 
menace to health. That this does not occur is proven by 
foul accumulations of sewage solids exposed at low tide 
throughout the inner harbor. 

As a matter of fact, the sewage does not pass entirely 
out of the harbor into Long Island Sound on a single ebb 
tide, as has been demonstrated by the movement of tidal 
floats, but to a material extent is pushed back into the 
upper harbor by the next flood tide, so that sewage solids, 
carried in suspension, are moved back and forth, and a 
considerable portion are finally stranded on the harbor 
floor with slackening of the current. 

This is particularly the case in the western part of the 
inner harbor, where the Shag Bank interferes with the free 
movement of the tides, and in the slips and undredged 


13 


portions of the rivers where currents are seldom sufficient 
to produce scouring velocities. 

Another item for special consideration is that compara- 
tively little fresh water enters the harbor to reinforce the 
scouring action of the ebb, and displace sewage laden water 
left in the harbor at low tide. The total watershed area 
of the three rivers entering the harbor is only 202 square 
miles, and of this some 53 miles are above impounding 
water reservoirs which retain most of the flow for months 
at a time during drought periods. Taking account of the 
watershed areas below the reservoirs, and using a yield 
of 0.4 cubic feet per square mile, which is conservative for 
dry weather periods, the runoff available for sewage dilu- 
tion would be equivalent to an average of about one and 
one-half times the sewage flow. It is, therefore, a factor 
of little moment. 

The phenomenon of surging back and forth of the tides 
is not peculiar to New Haven. In New York harbor, 
where displacement action is particularly favorable, due to 
the large flow of the Hudson River and cross currents of 
sea water entering through the Lower Bay and Long Island 
Sound, it is estimated that about 80 per cent. of the water 
entering on each flood has been in the harbor before and 
consequently carries some burden of sewage. 

In Philadelphia harbor it has been estimated that a par- 
ticle of sewage solids moves back and forth a total distance 
of 540 miles in progressing forward 17 miles in the Dela- 
ware from Philadelphia to Chester, and if not stranded 
would consume about 16 days in transit. 

The extent of organic pollution of the harbor water 
can be gauged by a deficiency of dissolved oxygen below 
the condition of practically complete saturation, which 
obtains in the open waters of the Sound. To determine 
the concentration of organic matter from sewage and 
industrial wastes, as reflected by oxygen depletion, fifty- 
two separate samples for analysis were taken on August 
27 and September 10, during varying stages of tide, at 
thirty stations in the outer and inner harbor. The results 
are summarized in the following table:— 


14 


Number 

Sampling Per cent. Saturation 

Stations Avg. Max. Main. 
Bradley Pt. to Lighthouse Pt. 4 88 100 65 
Nioriis: Cove <2. cere 2 63 64 62 
paldlyat te tocy Ort tialeiencgs 3 59 64 51 
Oyster Pt to (Cranes Barae ee 54. 66 34 
Parent arbOte oe oes ae 6 46 64 34 
(UIA PiaC IN IVels eee ee 4. A4. 57 39 
Mill Rivert ccevasie eae eyeee 7 15 35 O 


As a further direct measure of harbor pollution, ninety- 
eight samples for bacteriological examination were taken 
on the flood and on the ebb tide September 8 and 9, from 
twenty-five different stations. One sample was taken near 
the bottom and another from just below the surface at each 
station. Samples were examined to determine the relative 
presence of B. Coli, which is a group indicative of sewage 
pollution. The numbers of B. Coli, as summarized in the 
following table, were obtained by averaging the results 
of individual tests made with varying dilutions of sterile 
water. 


Number 
O B. Col per too C. C. 
Location of Stations Samples Flood Tide Ebb Tide 
Savin Rock to Lighthouse Point 52 495 320 
Sandy Point to Fort Hale...... 22 820 700 
Oyster Pointto; Crates Barta. ae 24 925 1000 


Samples taken during flood tide in the outer harbor 
show a greater B. Coli density than those taken on the ebb, 
illustrating the accumulative effect of pushing back into 
the harbor the sewage laden water brought down during 
the latter portion of the previous ebb. The greater density 
in samples from the inner harbor, taken during the ebb 
tide, are indicative of the effect of holding back sewage in 
the land-locked upper harbor during the quiescent period 
of high tide. 

It is worthy of comment that the U. S. Public Health 
Service standard for drinking water used on carriers in 


ee) 


interstate traffic is a content of 1 B. Coli per roo c. ¢.,, 
and that the standards proposed by the Association of 
State Sanitary Engineers for quality of water in swim- 
ming pools would limit the presence of B. Coli to less 
than 4 per 100 c. ¢. 


2.—SEWAGE TREATMENT PROGRAM. 


Available Sites. With the exception of the park prop- 
erty on the eastern shore, there are no large undeveloped 
tracts of land bordering on the harbor. Available sites 
elsewhere are restricted to the shoals near sewer outfalls 
outside the high water line. If all sewage were to be con- 
centrated at one point for treatment, expensive underwater 
collecting conduits would be required, and all the sewage 
would need to be pumped, as head consumed in the collect- 
ing lines would make sewage level in the treatment plant 
too low to permit gravity operation. These conditions are 
met by providing four treatment plants of which three, 
namely the Boulevard, Meadow and East Street plants, 
will be located adjacent to the existing outfall sewers and 
operate entirely by gravity, and the fourth or eastern shore 
plant will be constructed in or near the upper end of Nathan 
Hale Park, receiving sewage from the James Street, the 
Poplar Street, and the eastern shore districts, and will be 
the only one where sewage pumping will be required. 

Foundation conditions are such that plants must be of a 
compact type and supported on piles, which means that 
excavations must not be needlessly deep. 

Location near high value commercial and industrial dis- 
tricts and in the vicinity of residential and park areas re- 
quires that there be reasonable assurance of freedom from 
offensive odors in the immediate vicinity of the plants. 


Development of Sedimentation Process. A brief recital 
of the development of the sedimentation process will ex- 
plain the applicability of the particular type of treatment 
tank which is recommended. 


16 


About a generation ago treatment of sewage with 
chemicals to precipitate the solids was practiced at several 
places in Europe and in this country, but the expense of 
chemicals and cost of handling excessive quantities of 
sludge, which were produced, caused general abandon- 
ment of the process. Septic tanks which provided for re- 
moval of the solids by sedimentation in single story tanks 
came into vogue about 1895, and were adopted generally 
in Europe and this country for about 15 years. While 
these tanks brought about a reduction of from 45 to 60 
per cent. of the organic solids, the results were not entirely 
satisfactory, particularly because of odors and sudden 
lapses in efficiency when masses of solids digesting in the 
lower part of the tanks were lifted into the flowing sewage 
by gases of putrefaction and carried out with the effluent. 

These difficulties are partially overcome by two-story 
tanks, frequently called Imhoff or Emscher tanks, in which 
are diaphragms having a slot through which the sludge 
passes into a lower compartment as it settles from the sew- 
age. These tanks, since their rise to popularity in about 
1910, have been of much value, but along the populated 
water fronts of the large cities they are often at a disad- 
vantage, because of expense of construction, due to the depth 
of the tanks and the lack of adequate areas for drying 
sludge. 


Plain Sedimentation Tanks. During the past ten years 
both in Europe and in this country, plain sedimentation 
tanks have come to the front. In these tanks the sludge de- 
posited from the slowly moving sewage is promptly re- 
moved before onset of putrefaction with dispersion of 
offensive gases throughout the neighborhood, and occasional 
breaks in efficiency of sedimentation. Sludge removal is 
accomplished by mechanical concentrating devices of which 
there are several successful types available. 

A further advantage of these tanks is adaptability to 
arrangements for use of air, either as in the activated 
sludge process, or as in contact aerators, if in later years 


17 


it should be desired to carry purification one step further 
and treat non-settling organic impurities. 


Grit Chambers. The grit contained in storm water flows 
should be removed from the sewage before it enters the 
sedimentation tanks. Otherwise, this relatively clean sand 
and silt becomes a part of the sludge and adds to the 
difficulty and expense of sludge handling. Oil and grease 
should also be skimmed from the surface of the sewage 
either in the grit chambers, or the sedimentation tanks, or 


both. 


Disposal of Sludge at Sea. At many of the large 
European coast cities, such as London, Manchester, Dublin, 
Glasgow, and Southampton, sludge from the sedimentation 
tanks is taken to sea in self-propelled tank boats and dumped. 
In this country a similar procedure is in force at the Passaic 
Valley Joint Trunk Sewer disposal works, whereby under 
contract sludge is carried in self-propelled tankers and dis- 
charged at a point some seven miles southeast of Scotland 
Light, a distance of ten to twelve miles from the New 
Jersey bathing beaches. 

The method has been used in London for more than 
twenty years, a fleet of six steamers carrying the sludge to 
Barrow Deep, off the mouth of the Thames River, a dis- 
tance of about fifty miles from the sedimentation works at 
Barking and Crossness. The boats steam slowly when ar- 
riving at the disposal area, and cover a distance of approxi- 
mately ten miles while the sludge is being discharged from 
the tanks. Careful investigations have indicated absence 
of undue pollution of the sea water, and the results secured 
have been described by Sir Alexander Houston as “satis- 
factory.” 

We estimate that at New Haven the quantity of sludge, 
after removal of a large proportion of the supernatant 
liquor by sedimentation and decantation, would amount to 
about 71% cubic yards to the million gallons of sewage, 
or from 200 to 250 cubic yards a day during the first few 


18 


years. If a second-hand, self-propelled oil tanker, having 
a capacity of from 750 to 1000 cubic yards, were purchased, 
only about two trips a week would be required for several 
years. 

To avoid possible pollution of shellfish areas and bath- 
ing beaches, it would be advisable to dispose of sludge in 
the open sea east of Long Island, at a distance of from 60 
to 65 miles from the sedimentation plants in the upper end 
of the harbor, 


Separate Sludge Digestion. For purposes of record, a 
statement is given regarding the alternate process of 
separate sludge digestion, although it is not the project 
recommended in this report. If this process were to be 
adopted, the sludge removed at the plain sedimentation 
tanks would be pumped to a battery of tanks east of the 
City, where by suitable mixing and other control operations, 
the process of digestion would be completed without com- 
plications due to odors. 

The principles governing the successful use of these tanks 
have been developed in England during the past 14 years, 
and at over-a score of comparatively recent installations 
in Germany and in this country. 

Of particular advantage is the fact that sludge removed 
from tanks in built-up districts can be pumped to separate 
digestion tanks, located in suitably isolated areas, where 
sludge drying beds may be provided. With adequate design 
of digestion tanks and proper operation, the sludge can 
be so prepared that the drying can be effected without 
offensive odors. 


Improvements in Sludge Digestion. The collection of 
all gases of putrefaction for burning on the grounds, use 
for power about the plant, or for sale, is now on a practical 
footing. In fact at Birmingham, England, it has been 
used for four years for operating a combustion engine, and 
in Germany it is sold to the local gas works in a dozen or 
more instances. The main point for emphasis is that by 


£9 


collection and burning, the gas is not disseminated through 
the air to cause complaint; the utilitarian phase is of 
secondary importance. 

By placing gas collectors below the surface of the liquid, 
scum is kept away from the air and digests as thoroughly 
as solids settling to the bottom of the tanks, thus removing 
another troublesome factor of earlier tanks. 

Control of the ripening stage of sludge, made possible 
through recent research, has removed complications due to 
acid formation which in the past were the cause of occa- 
sional irregularities, and oftentimes necessitated discharge 
of odorous sludge. 


Sludge Dewatering. Power presses of various types, 
filters and heat dryers have been brought to a moderately 
satisfactory standard for dewatering activated and chemical 
precipitation sludges. With the possible exception of a 
complicated and cumbersome centrifugal dryer which was 
installed at a few locations, the accepted method for de- 
watering sludge from sedimentation tanks is through the 
use of underdrained sand or cinder beds. There are scores 
of such installations in service, for the most part uncovered, 
but in a few recent installations provided with glass roofs 
of the greenhouse type. 

Sludge is reduced to a condition readily removable from 
the beds with a spade, and can be used as fill about the 
plant. It has a slight fertilizer value. The sludge bed 
area required ranges from 0.6 to 1.0 square feet per capita 
for northern latitudes for open beds, and perhaps % to % 
as much for covered. The effluent from the beds is 
putrescible, but can be readily purified in small filters, or 
returned to the tanks for further treatment. 


Miles Acid Process. The investigations at New Haven 
during 1917-18 which led to recommendation for adoption 
of a modified chemical treatment process, known as the 
“Miles Acid Process,” for the East Street sewage, with 
possibility of additional installations at the other outfalls, 


20 


were made at a time when conditions were abnormal due 
to activity of ammunition plants discharging great volumes 
of industrial wastes into the sewers. This process then 
seemed of particular merit, because through it alone was 
it deemed possible to satisfactorily treat sewage having a 
high acid content and carrying a considerable proportion 
of wastes which would interfere with biological action in 
the ordinary treatment process. At that time also market 
conditions were favorable for disposal of grease and 
fertilizing materials which would be produced in varying 
amounts as by-products. 

With the termination of the war, the quantity of indus- 
trial wastes having an inhibiting effect on biological pro- 
cesses was considerably reduced, and methods for treatment 
of such wastes, before discharge into the sewer system 
have since been developed to such an extent in this country 
and abroad that their presence is no longer a controlling 
factor. Furthermore, in recent years the markets for by- 
products which would be produced by this process have 
not been such as to indicate any financial savings through 
its adoption. The process has not made progress to the 
extent of adoption for large size installations. 


Conclusions. From the standpoint of elimination of 
sludge deposits from the harbor bottom and required reduc- 
tion of bacteria, sedimentation is the only process which 
will assure satisfactory results and benefits commensurate 
with the cost. 


3.—TREATMENT WorxKs RECOMMENDED. 


The principal features of the treatment process recom- 
mended, namely plain sedimentation, and chlorination during 
the bathing season with disposal at sea, together with the 
alternate method of digestion and drying the sludge at a 
location outside the City limits, are briefly discussed in the 
following paragraphs:— 


Capacities. In general the first construction of treatment 
plant units should be adequate for the sewage flow to be 


2I 


expected during a period of 10 to 15 years, or roughly 
until about the year 1940, assuming early inception of the 
construction program. 

In addition to dry weather flow, it is proposed to divert 
to the sedimentation units the first flush of storm water 
from the streets in suitable volumes. 

Needed capacities of the various treatment works ex- 
pressed in million gallons daily, under 1940 conditions, are 
estimated as follows:— 


Eastern 

Rates of Flow Boulevard Meadow East Shore 
_ Average Daily .. 85 5.2 ‘i 8.6 
Business Hours .. 12.0 8.3 17.0 11.8 


Elevations. Gravity flow can be obtained for all plants, 
excepting that for the East Shore. Surface level in the 
sedimentation tanks would be approximately that of sewage 
flowing in the sewers during low tide, the tank walls, how- 
ever, extending to elevations above maximum recorded tide. 
During high tide, level in the tanks would rise, but as the 
design would be such as to produce a continuous outward 
flow, there would be no material interference with effective 
sedimentation. Outlet conduits would be equipped with 
suitable tide gates to prevent entry of harbor water during 
high tide. 


Regulators. Suitable regulators should be located in the 
various outfall sewers to prevent backflooding of the sedi- 
mentation tanks during high tides, and to divert the dry 
weather sewage flow and the first flush of storm water. 


Screens and Grit Chambers. Coarse screens of the bar 
type would be provided for removal of large suspended 
solids and floating materials generally of inorganic origin. 
Screenings would be of small volume and should be in- 
cinerated or buried. 

Following the screens, sewage would pass through grit 
chambers where the flow would be reduced to a velocity 
of approximately one foot a second, and mineral matters 


23 


scoured from the streets would be deposited, thus preventing 
complications in the sedimentation and digestion tanks due 
to their presence. The deposited materials are mostly 
relatively clean sand. Suitable equipment should be pro- 
vided for mechanical cleaning of the grit chambers. 

Here also would be located appropriate skimming devices 
for removing oil from the surface of the sewage. 


Sedimentation Tanks. The sedimentation tanks would 
be designed to provide a sedimentation period of from one 
hour and three-quarters to two hours for the average flow 
of sewage, when population has reached the ultimate density. 
During business hours, when sewage flow would be at a 
maximum, the detention period would be reduced to about 
one hour and a quarter, depending upon the stage of the 
tide, and at times of storm when the first flush of gutter 
water reached the plants, it would be further reduced to 
approximately one hour. The average velocities of flows 
through the tanks under the above conditions would range 
from about % to % inches a second, or an average of 
about 75 feet per hour. 

The tanks would be equipped with mechanically operated 
scrapers and pumps for removal of sedimented solids, as 
well as with suitable apparatus for chlorination of the 
effluent. Preferably they should be so designed as to per- 
mit addition of apparatus for use of air at a later date. 
should further purification of the sewage be deemed 
advisable. 


Sludge Disposal at Sea. As previously stated, we pro- 
pose to use a second-hand oil tanker of from 750 to 1000 
cubic yards capacity, propelled by steam or Deisel engine, 
depending on what type of boat can be most advan- 
tageously purchased. A new boat is not required for this 
service where it will not meet particularly difficult con- 
ditions of wind and weather. The capacity of the boat 
and the sludge decantation tanks would be sufficient for 
a five day collection period, so that it would not be neces- 


TD gm 
23 


sary to make trips on very foggy days, or under extreme 
weather conditions. Short dredged channels would be 
required to the sedimentation tanks, and piers suitable for 
use of the sludge boat. At times when the boat would be 
laid up for repairs or overhauling, which periods should 
be short and infrequent, bottom dumping scows and tug 
boats could be used. These are readily procurable at all 
points along the coast. 


Separate Sludge Digestion. The following paragraphs 
are descriptive of sludge force-mains, sludge digestion 
tanks, and sludge beds, which would be required under 
the alternate process of separate sludge digestion. The 
descriptions are here given principally for record purposes. 
The necessary construction cost of the units suitable for 
1940 conditions is estimated at $755,000. 


Sludge Force-Mains. Pumps would be installed at each 
sedimentation plant for delivering sludge through branch 
lines to a main pipe line laid in duplicate, some 8 inches 
in diameter, extending to the sludge digestion tanks. 
Sludge would be withdrawn from the different tanks for 
periods of two or three hours each day on a pre-deter- 
mined schedule, so that friction complications, due to 
simultaneous operation of the pumps at different plants 
would be avoided. One of the force mains would ordi- 
narily be used for returning to the sedimentation tanks 
the effluent from the sludge beds and excess water from 
the digestion tanks, but would be available as a sludge 
force main in event of serious leaks developing, or other 
emergency conditions. Sludge lines would be provided 
with hatchways at intervals of one-half mile or less to 
facilitate cleaning or repair operations. 


Sludge Digestion Tanks. These tanks would be ar- 
ranged in batteries, and equipped with covered channnels 
or partitions somewhat on the principle of small Imhoff 
tanks to assist in separation of excess water from the sludge 


24 


as added to the various units. Piping arrangements should 
be such as to facilitate transfer of sludge from one tank 
to another, for mixing partially digested with fresh in- 
coming sludge, and for liming, as desired for control of 
ripening operations. Excess water would be returned 
through the force mains to the sedimentation tanks. 

Suitable devices should be provided for preventing rise 
of scum to the surface of the liquid, and for collection of 
the gas for burning, or use for power or lighting purposes 
at the plant. 

The tanks would be entirely surrounded and covered 
with earth embankment to conserve the heat of incoming 
sludge, so far as possible, to facilitate digestion during 
winter temperature. The first installation should provide 
a total sludge capacity of approximately one-half million 
cubic feet, or two cubic feet per capita for the estimated 
1940 contributary population. 


Sludge Beds. Sludge beds would be divided into several 
units, and have a total area of approximately 4.5 acres, 
or eight-tenths square foot per capita of contributing 
population. Beds would be of underdrained sand or 
cinders, would be uncovered, and provided with simple 
mechanical equipment for removal of dried sludge. The 
effluent from the beds would be returned to the plain sedi- 
mentation tanks, together with the excess water removed 
in the sludge digestion tanks. Dried sludge would be dis- 
posed of in fills around the plant, or might possibly be 
taken by farmers, in the vicinity, for fertilizer. 


4.—STORM WATER RELIEF SEWERS. 


In general the main sewers and principal branches 
following the Chesbrough plan, inaugurated in 1872, were 
designed to care for a rainfall of one inch an hour, with 
some allowance for variation in the slope of the ground 
and the completeness of development which would affect 
the rate of flow of storm water to street inlets, and also 
the proportion which would be absorbed by the ground. 


25 


In providing for relief sewers to take care of storm 
flows in locations where existing sewers were found in- 
adequate, the so-called “rational’’ method of analysis was 
used to determine the total volume of storm water which 
might be expected in any particular location, and from 
this figure was deducted the capacity of existing sewers, 
the remainder being the measure of relief required. 

Records of the local office of the U. S. Weather Bureau 
for the past twenty-five years were tabulated to show the 
intensity and duration of storms which might be expected 
at average frequencies of 1, 5 and 10 years, and appear in 
the following table:— 


Precipitation in Inches an Hour 


Duration Once in Once in 
in Minutes Annual 5 Years 10 Years 
118 Galatry td A ak ei 270) 3.95 4.30 
GAUDI, 20 Ue ance 1.75 2.68 2.98 
SY Oh: Kapaa ts ie Sl a ae 1.40 2A 260 
ER Mere tial onc 1A) Gey 1.80 2.08 
ice) stared ants ae 0.95 1.60 1.80 
8 BA el Mace a ARE a O Kr 6 Ten 1.35 
1220} yO I Nene a fe eR 0.55 0.95 I.05 


Our staff found that typical blocks show relative pro- 
portion of impervious areas, ranging from 30 per cent. to 
45 per cent. for residential, and from 50 per cent. to 90 
per cent. for closely built up commercial and industrial 
districts. Runoffs for the particular districts were selected 
from these ranges to conform to development which might 
be reasonably expected to occur within the next 40 to 50 
years. 

In general, relief sewers are provided to care for the 
runoff of storms having an average frequency of once in 
5 years. In the Meadow Street district, where property 
values are relatively high, and where automatic valves have 
been installed with fair success in most of the deeper 
cellars, relief sewers are provided on the basis of the storm 
which might be expected once in 10 years, and permitting 


26 


both existing and relief sewers to operate under a pressure 
equivalent to a 50 per cent. surcharge during such a storm 
when the district shall have attained the density of develop- 
ment expected in 1970. 


Storm Water Overflows. In several instances the sills 
of storm water overflows are at such slight elevations above 
the invert of the main sewer that the overflow operates, 
discharging mingled sewage and storm water into the 
rivers during storms of slight intensity when there is but 
little dilution. The sills of some overflows are below the 
elevations of high tides, so that inflow of salt water from 
the rivers would interfere mechanically with the normal 
operating program of the sedimentation basins. 

The sills should be adjusted to prevent operation of the 
overflows until the main sewer is carrying a volume 
equivalent to the estimated 1970 sewage flow, and storm 
water equal to the runoff from a storm having an intensity 
of about 0.04 inch an hour. Under such conditions the 
dilution would be sufficient to avoid undue sludge deposits 
in the vicinity of the overflows. Suitable automatic gates 
should be placed at overflows having sills below elevation 
of high tides. 


Location of Relief Sewers. Routes for necessary relief 
sewers classified by the various sewerage districts, and for 
immediate and future construction would be as follows: 


IMMEDIATE CONSTRUCTION. 
Meadow Street: District: 


A main outlet in State Street extending from the harbor 
to Crown Street, and in Crown to Orange Street, with 
branch in Crown to Temple Street, and in Orange to Elm 
Street, thence extending in Elm Street to York Street. 


East Street District: 


A main outlet in State Street extending from Mill River 
to Edwards Street, and in Edwards Street to Orange 


27 


Street, thence in Orange to Pearl Street, and in Pearl to 
Lincoln Street, and in Lincoln Street to junction with the 
present 60 inch sewer at Trumbull Street. Branches would 
extend in Foster and Orange Streets from Lawrence to 
Edwards Street, in Edwards from Whitney to Orange, and 
in Whitney from Edwards to Lawrence. 


IO TO 20 YEAR PROGRAM. 
Boulevard District: 


Derby Avenue from George St. to Mead Street. 

Dixwell Ave. from Dorman St. to W. Division St., 
and W. Division St. from Dixwell Ave. to Shelton 
Avenue. 

From Boulevard and Elm St., through Boulevard, 
Sherman, Elm, Norton and Edgewood Sts. to West 
River. 

From Shelton and Argyle Streets, through Shelton, 
Munson and Crescent Streets, to Beaver Pond outlet. 


Meadow Street District: 


From Elm and University Place through Elm, 
Dwight, Edgewood, Howe, and Crown to Crown and 
Temple, with branches in Chapel, Park and York 
Streets. 

From Oak and Davenport through Oak, Congress, 
Commerce, Whiting and Meadow Streets to the harbor, 
with branches up Water to Silver, up Union to Port- 
sea, and up Columbus to Lafayette, and a sewer in 
Silver St. from Liberty to Hill Street. 


East Street District: 


In Water St. from Olive to Chestnut St., and from 
Franklin to Chestnut St., and in Chestnut St. from 
Water St. to the harbor. 

In Division St. from Winchester to Shelton Ave., 
and in Shelton from Ivy to Argyle. 


28 


In Orange St. from Canner to Mill River. 
In East Rock Road from Everit to Mill River. 


Fair Haven District: 


In Blatchley from Grand to the harbor, with branches 
up Exchange to Poplar, up Grand to Fillmore, up 
Saltonstall to Poplar, and up Fillmore from Grand to 
Pine. 

In State St. from Grace to James Street. 

In Exchange St. from James St. to Mill River. 

In James St. from Clay to Grand Street. 


Treatment of Storm Water. Even though the first flush 
of storm water is diverted to sewage treatment works, the 
flow passing through the overflows into the streams carries 
some organic solids, and if the receiving body of water 1s 
small there is possibility of some objectionable deposits 
occurring in the vicinity of the overflows through a term 
of years. Under local conditions two such instances may 
develop, the first at the new relief overflow recommended 
at State and Edward Streets in the East Street District, 
where the flow in Mill River is slight, due to storage of 
water in Lake Whitney; and the second at the Crescent 
Street overflow into West River in Beaver Pond Park. 

At these locations it will be advisable in coming years 
to install large grit chambers or detritus tanks to reduce 
the velocity of flow during storms sufficient to cause sedi- 
mentation of solids which would be liable to form objection- 
able deposits. 


5.—EXTENT OF ADOPTION OF SEPARATE SYSTEM OF SEWER- 
AGE IN FUTURE. 


In general, districts which are now sewered on the com- 
bined system must so continue in the future for economic 
reasons. To install storm water conduits throughout such 
districts to collect water now reaching street inlets, and a 


29 


sufficient portion of roof water, to adequately relieve exist- 
ing sewers from overloading, would require so many miles 
of sewers and such expense for changing connections from 
individual houses, that the total would be greater than the 
sum required for reasonable relief of the combined system. 

The present policy of constructing separate sanitary 
sewers in Westville and Hamden should be continued, and 
should be adopted for the Fair Haven East wards, as well 
as the portions of East Haven, North Haven and Wood- 
bridge, which will ultimately be included in the sewerage 
district. ) 

By adoption of the separate system in these outlying dis- 
tricts, present expenditures will be held at a minimum 
because of the relatively small size of sewage sewers as 
compared with combined sewers. 

In construction of sanitary sewers particular care 1s 
necessary to secure tight joints so as to keep infiltration of 
ground water at a minimum, otherwise an unjustifiable 
burden will be placed on the treatment plants. 

Storm-water drains of moderate length and size, dis- 
charging into nearby watercourses, could be provided at 
reasonable cost, as required to meet the demands of par- 
ticular sections, but general construction of storm water 
conduits could be postponed for many years.’ The sums 
represented by the savings in interest charges on sanitary 
sewers and such storm sewers as it would be necessary to 
construct at present, as contrasted with general installation 
of combined sewers throughout these outlying districts, 
would be considerable. 

Small sanitary sewers should be installed along Mill River 
Street north and south from Grand Avenue, to collect 
sewage now entering Mill River through private sewers. 
A small automatic pumping station would raise this sewage 
to the elevation of the East Street sewer, and a similar 
pumping station would intercept sewage reaching the Grand 
Street overflow on the east side of the river. 

Industries along Mill River and the harbor now discharg- 
ing directly through private sewers should be required to 


30 


connect to the public sewers, installing small pumping sta- 
tions on their own property, if necessary, to raise sewage 
to level of the public sewers. In many instances industries, 
by rearrangement of sewers, can continue to discharge cool- 
ing water directly into the harbor or rivers through private 
sewers, together with a large portion of the industrial waste 
flow, which is practically free from polluting matters, leav- 
ing only a relatively small volume of rather concentrated 
wastes to be discharged into the municipal sewers. 


Extent of Future Sewerage District Outside City. In 
determining territory outside the present City limits, which 
should be included in a general sewerage project, considera- 
tion has been given not alone to natural drainage and to the 
economic features which would influence future develop- 
ment, such as railroad and trolley lines, through highways 
and present use of the land, but also as to whether sewage 
from these outlying districts could better be treated in 
separate plants. 

The boundaries of this territory, as determined by these 
studies, are shown on Plate II. 

The portion of East Haven situated west of a line repre- 
sented by Morris, Kenneth, Prospect and Hemingway 
Streets, and south of the railroad and territory north of 
the railroad west of Laurel and Bradley Streets would be 
tributary to the Fair Haven East sewers. 

The districts of Hamden and North Haven bounded by 
the railroad and the Quinnipiac on the east, and West Rock 
Ridge on the west, and extending northward to a line 
roughly represented by Circular Avenue and Benham 
Street in the northwestern portion; Dickerman and Ives 
Streets in the north central section, and Broadway and 
Ridge Road in the northeastern portion, would become 
tributary to the James Street, East Street and Boulevard 
sewer systems. 

The district of Woodbridge northwest of the City on the 
watershed of West River, and extending as far north as 
Lake Dawson, would become tributary to the Boulevard 


31 


system through connections to sewers on Whalley Avenue, 
Chapel and Derby Streets. 

Sewage from West Haven is now treated at plants 
located along the water front. There is no present need to 
abandon these plants and deliver sewage to the New Haven 
treatment works. 


Eastern Shore Pumping Stations. Owing to the topog- 
raphy in the districts east of the harbor and the Quinnipiac, 
it will be necessary to pump sewage from three small 
districts. The pumping stations as indicated on Plate II, 
will be located as follows:— 


Along Morris Creek at intersection of Thompson Avenue, 
to handle sewage from the Lighthouse Point section. 

Near Pope Street and Woodward Avenue, to handle 
sewage from low-lying streets in that vicinity. 

Near intersection of Essex Street and Quinnipiac Avenue, 
to receive sewage from low-lying streets in the upper portion 
of the district and deliver the same into the receiving well 
of the Forbes Avenue pumping station for delivery to the 
treatment plant, together with the flow from the James and 
Poplar Street outfalls. 


6.—INCREASE OF POPULATION. 


In estimating future population, consideration has been 
given to the rate of increase of the various wards of the 
City in the past, and to the probable changes in character 
of development in the various districts which will in- 
fluence the density of population in City and suburban 
districts which must be considered as integral parts of the 
municipal sewerage problem. 

Comparisons have also been made with the rate of in- 
crease of New Haven County, the State, the larger cities 
of New England, and with a group of similar cities through- 
out the country after attaining the present population of 
New Haven. Estimates of population increase prepared 
by the Southern New England Telephone Company and 
other public utilities have likewise been studied. 


32 


_ Based on these various studies, the following estimate of 
the population of the City and portions of the suburbs 
resident in the sewerage districts has been prepared:— 


Location 1930 1940 1950 1960 I970 
New Haven.. 192,500 222,000 249,500 277,000 304,000 
Hamden.... 8,500 ~18,000) 25,500 34,000 ° 43,006 
North Haven. ee 500°. 1,000. 1,500. 227068 
Rast shlaven so. ark ~ asa 20,5002. 7,500. oer 
Woodbridge . pe Te ey 500°) 715000 1j00e 

SOTA lien eae 201,000 240,500 283,000 321,000 358,000 


Population of the City arranged according to the main 
sewerage districts, as recorded by the 1920 census, and as 
acaan for 1970, with corresponding teas: per acre, 
appears in the following.table:— nh 


1920 I970 

Persons Persons per Acre 
e Population per Acre Population Gross Net* 
boulevard wees 56,037... 11.8. 5 328,700. (20; See 
NMeadow!.«0- etn 2O 110. ef0e3 33,700) 50.0; eee 
Pasty. 7) cae A AO Mee OeL. 86,500 48.3. 51.0 
Jamnes?.”, {eee AAO elo 17,700) 20.4 gee 
Poplarss it Wee 570 mae eae, 15,200, 32.870 ieee 
Fair Haven Face 7,000 ort 22,200 6.7 7.4 


Entire City %'.162;537 “¥ 14-2) 204,000" (260 Gren 30.8 
* Net area = land area minus area of parks and City 
squares. 


Commercial and Industrial Areas. In making studies of 
the probable location and extent of commercial and in: 
dustrial area, the availability of rail and water transporta- 
tion facilities, proximity of residences of industrial workers, 
and of a source of water supply for industrial purposes, 
as well as arrangement of through highways and street car 
lines, were given consideration. The probable extent of 
these areas, as determined by such studies and consultation 
with representatives of the City Planning Commission, ‘is 
shown on Plate III. 


PRESENT & ASSUMED FUTURE 


COMMERCIAL & INDUSTRIAL DISTRICTS 
LEGEND 


E3926 Commercial Areas 

ERB Additions by/970 to 1/926 Commercial Areas 
F289 /926 Industrial Areas 

ESAdditions by 1970 ta 1926 Industrial Areas 


34 


The totals for the various sewer districts of the City 
appear in the following table:— 


Commercial Industrial 
Areas in Acres 
District Present 1970 Present 1970 
HOU var e eC een 76 291 83 166 
ECAC OS: a wine rene ei nomen tale 289 409 14 14 
Bast sown. cee eee ae T22 247 265 438 
TAMmeS cri tasty ie oe Sey ¥f SI ae inZ 
ODL AT A iis need tae cee tre 33 85 39 Za 
Pairilayen; act a0. nas ee, 3 102 120 621 
Ota ease hin mae rae eters \arrals 592 1467 


7.—SEWAGE FLow. 


In addition to the flow from public sewers, it is estimated 
that 250,000 gallons of sewage a day enter the Quinnipiac 
River; that 1,650,000 gallons enter Mill River, and 940,000 
gallons enter the harbor through private sewers from resi- 
dences and industries. This additional contribution of 
2,840,000 gallons is derived in part from private wells, 
and in part from the public water supply. 

Weirs were installed in the main sewer outlets, and 
sewage flow measured for a period of about eight weeks 
from May 23 to July 17. Automatic recording gauges 
were used at the Boulevard, Meadow and East Street outlets, 
and hand gauges at the remaining three. Readings during 
rains or when high tides interfered with free discharge 
at the outlets were disregarded. 

The rates of flow for the various sewers, expressed in 
million gallons per 24 hours, and exclusive of the 2.84 
m. g. d. noted above, appear in the following table:— 


Average Average 
Average Week-Day Night Flow 
Daily 9.30 A.M. 2A.M.to 
Sewer Flow to 5.30 P.M. 5A. M. 
BOwlevardy ae. 5.59 7.79 2.89 
WLEACOW “eh tuarea ec 7 a7 3.45 1.48 
SEALE IS We Arrant ch 1.90 0.60 
PCS tet. ie teen oa 9.31 14.02 4.05 
POUeSa, eee eto) 1.34 0.36 
Poplarg eae wecacO Be 0.72 0.15 


A Oba ia ea 29.22 9.53 


35 


Some 48 per cent. of the entire sewage flow occurs during 
the eight maximum hours of the day, and during these 
hours the rate is 44 per cent. greater than the average 
for the entire day. 

The total average sewage flow was estimated as 24.8 
million gallons daily in 1916, and as 29.5 million gallons 
daily in 1917, which figures are respectively 22 per cent. 
and 45 per cent. higher than found in 1926. Present water 
consumption figures likewise show a falling off, the total for 
the entire New Haven district in 1925 being approximately 
the same as in the year 1915, and considerably less than 
for any subsequent year. ‘The reduction in sewage flow 
is partly due to shutting down of war-time operations in 
the industries, and partly to the more extensive use of 
water meters throughout the City. 


Industrial and Commercial Sewage Flow. Water con- 
sumption records of the larger industrial concerns through- 
out the city were investigated, and the quantity of water 
pumped from various private supplies was added to the 
water purchased from the public supply. Deductions were 
then made to represent the quantity which would not enter 
the sewer system, and a factor applied to give the rate 
of discharge during normal operating hours of the plant. 
This figure was applied to the total area of the plant and 
indicates a rate of 17,000 gallons per acre daily, as the 
average contribution from industrial areas. For future 
areas which will not attain full development for many years, 
an allowance of 12,000 gallons an acre is considered as 
sufficient. 

In the case of certain industries where unusual quantities 
of water are used, specific rates should be applied rather 
than the average. 

A similar procedure for the larger commercial establish- 
ments in the central business district indicates an average 
of 15,000 gallons an acre discharged into the sewers at 
a rate of 30,000 gallons an acre when the district shall 
attain its full development. For small stores in outlying 
districts, a rate of 5,000 gallons an acre a day should be 
made in addition to the domestic sewage for the district. 


30 


Domestic Sewage Flow. Analysis of water meter records 
indicates a consumption for domestic and commercial pur- 
poses equivalent to 58 gallons per capita daily for the entire 
population supplied with water. A census of several hun- 
dred homes in different portions of the City covering the 
highest, middle, and poorer types, gave an average water 
consumption of 70 gallons per capita daily for the highest 
class of homes, and for the middle and poorer classes taken 
together, an average of 42 gallons per capita. 

Measurements of sewage flow from purely residential 
districts containing the highest class of homes, indicated 
a flow of 67 gallons per capita daily, after making suitable 
reductions for ground water entering the sewers. 

Considering the relative proportion of the various classes 
of homes, 44 gallons per capita daily was selected as a 
reasonable figure to represent the average daily discharge 
from the entire district. 

As most cities show a tendency to increasing use of 
water for domestic purposes, because of better sanitary 
standards and general adoption of modern plumbing, 
domestic sewage flow is considered as increasing to an 
average of 50 gallons per capita daily by 1940, or some 
I5 per cent. greater than at the present time. 

In order to allow for daily and monthly variation, a 
sewage flow of 65 gallons per capita, or approximately 
130 per cent. of the 1940 average was selected to represent 
1970 conditions. 

Rainfall during the period of sewer gaugings was below 
the average for the year, and accordingly the minimum 
recorded flows cannot be considered as representing ground 
water infiltration during wet seasons. These flows in 
gallons per 24 hours per acre of drainage area, as recorded 
for the various districts, appear in the following table:— 


District Rate per Acre 
Boulevard uaa ce eee ee SAG He 442 
Meadow and ‘State: cn te) aoe ree 307 
JAMNOS ig Aiton bocce ats oo iets cee ee ete 193 


37 


An allowance of 500 gallons an acre for the entire 
district is believed to be sufficient for ground water in- 
filtration under average conditions. 


8.—COMPOSITION OF SEWAGE AND INDUSTRIAL WASTES. 


In view of the extensive analytical work during the in- 
vestigation in 1918, it was only necessary at this time to 
make analyses to check the general characteristics of the 
sewage flow to make certain that no unexpected changes 
had occurred. 

As noted in the previous investigation, New Haven 
sewage is somewhat weaker than found in many of the 
larger cities having combined systems of sewers. This is 
due in part to the preponderance of metal working indus- 
tries in which the volume of industrial waste, although 
comparatively large, contains but little organic matter, and 
in part to the fact that certain industries having wastes 
relatively high in organic content have private sewers lead- 
ing directly to the rivers or the harbor. 

There is also considerable depositing of solids in the 
sewers, as evidenced by records of the Superintendent of 
Sewers. A material percentage of these solids is undoubt- 
edly flushed through the sewers during the first periods of 
heavy precipitation, and would reach the treatment works. 
Allowance for these conditions must be made in consider- 
ing the results of analysis of samples taken during short 
periods or at irregular intervals. 

The total solids ranged from an average of 1027 parts 
per million in the East Street sewer to 2710 p. p. m. in the 
Poplar Street sewer. Suspended solids ranged from 100 
p. p. m. in the East Street sewer to 183 p. p. m. in the 
James Street sewer. 

The analytical work was carried on during the latter part 
of August when the rate of ground water flow was above 
the average for the entire summer, due to the unusual 
prevalence of rains during the month. It also was just fol- 
lowing a period when the sewers had received a thorough 
flushing by intense storms.” 

As is the case in other large municipalities, the sewage 
contains a considerable proportion of fats and mineral 


38 


oils, the content of ether soluble matter ranging from 24 
to 54 p. p. m. 

As a measure of the putrescible character of the sewage, 
biochemical oxygen demand tests were made during the 
daylight hours and gave an oxygen demand equivalent to 
.22 pounds per capita daily. These figures correspond 
closely with results obtained in other cities for the average 
discharge from combined sewers. 

Owing to the use of harbor water for cooling purposes 
at one of the industries, chloride content of the East Street 
sewage was greatly above that for the other sewers, ranging 
as high as 3540 p. p.m. When this cooling water does not 
reach the East Street sewer, chlorides drop to about 68 
parts per million. Should the mineral solids, due to this 
waste, prove at all troublesome in sewage treatment, their 
elimination could be easily effected by return of the cooling 
water to the harbor instead of its discharge into the sewer. 

As in previous investigations, copper was found in the 
East Street sewage due to wastes from a few industrial 
establishments, where brass and copper are cleaned by acid. 
The germicidal effect of this acid waste was plainly notice- 
able in the bacteriological analyses, the total number of 
bacteria living at temperatures of the human body being 
only 2,000 per c. c. in a sample taken from the sewer below 
one of the industrial plants, in contrast to a content of 
400,000 per c. c. in a sample from the same sewer above 
the industry. 

Laboratory experiments on samples of wastes from these 
different industries indicated that they can be treated at a 
reasonable cost before discharge into the sewer system, and 
the copper content reduced to a degree such that it will 
not be detrimental to the ordinary methods of sewage 
treatment. As a matter of fact such treatment is being 
successfully carried on at industries in England and in 
Germany, and at other points in this country. 

Analyses were made of the wastes from numerous other 
industries in the City, but in no case would the results in- 
dicate a discharge into the sewers, or directly into the 
stream, of wastes which would interfere with, or materially 
burden, sewage treatment processes. 


oo 
ACKNOWLEDGMENTS. 


During the progress of our investigations we have been 
aided by previous studies of the New Haven sewerage 
problem, and particularly by the investigation of a Citizens’ 
Committee in 1917-18, under the Chairmanship of Pro- 
fessor C. E.-A. Winslow, and the report on possibilities of 
treatment of the sewage prepared by City Engineer Nettle- 
ton in September, 1925. 

We wish to express appreciation of the courtesies ex- 
tended by Mr. E. S. Nettleton, City Engineer; Mr, H. J. 
Kellogg, Engineer in Charge of the Sewer Division; Mr. 
C. W. Merrells, and other Assistant Engineers of the 
Bureau of Engineering; Mr. W. C. Kinney, Superintend- 
ent or sewers, Dr. J; L. Rice, City Health Officer, and 
the various inspectors of the Health Department. 

The field investigations in New Haven were in immediate 
charge of C. A. Emerson, and the principal members of our 
resident staff were G. S. Long, L. L. Campbell, and J. S. 
Parker, Jr. Analytical work was performed by A. F. 
Dolloff, L. E. Steiner and G. L. Frear. 


40 


SUPPLEMENTARY: | DATA! FILED “WITH Gli 


No. 


. Map Showing Boundaries of Sewerage Districts. 
. Tabulation of Measurements of Sewage Flow. 
. Estimated Population Densities for Various Sewerage 


ENGINEER. 


DESCRIPTION. 


Districts. 


. Estimated Domestic, Commercial & Industrial Sewage 


Flow. 


. New Haven District Water Consumption Records. 
. List of Replacement Sewers. 
. Details of Routes and Sizes of Storm Water Relief 


Sewers. 


. Notes on Removal of Accumulations from Sewers. 
. Notes on Sludge Soundings in Harbor. 
. Curves Showing Intensity of Storms to be expected at 


Intervals of 1, 5 and I0 years. 


. Details of Analysis of Sewage. 

. Details of Analysis of Industrial Waste. 

. Details of Dissolved Oxygen Tests in Harbor. 

. Details of Bacteriological Examination of Harbor 


Water. 


. Plant Cost of Sludge Digestion and Dumping at Sea. 
. Cost-of Pumping Stations and Intercepting Sewers. 


A 
Tea 
m) wie % 


; 


